Needing help solving severe creosote problems with my Seton Wood Boiler

[tigermaple]

I installed my GW in 3/07 and the first year was hell because I believed all the misinformation from the company and wasted some serious coin. Lucky I found my way here. First off, I have never taken my GW apart and cleaned the back hex ever (but I did have an overheat a couple years back that cleaned her up nice) I have no mixing valve or plate exchanger. No gaskets, but I did seal leaks. I have a seldom used draft inducer and 16' of chimney, no cap. The primary loop is 350'. The water temp in almost never at 180 in the morn, more likely 125º, but aways has enough coals to refire. The large house is 72ºI have no storage. But I do in a sense, and I believe this is the key to GW's and most wood burning boilers, old fashion cast iron radiators. I started replacing baseboard with cast iron in 2008 and what a difference. Now I have 18 of various sizes and couldn't be happier. My storage is in cast iron plus the water inside. They heat until the water is below a 100º and it seem the more the better. Only problem is price. In 2008 I was getting beautiful ornate 10 fin rads for 25 bucks, now the price is closer to 250 and they are harder to find. Plain ones are costing more also. There was a thread here a while back and someone was debated buying some rads cheap, well I would have bought em all if I lived nearby. As far as I am concerned cast iron rads are must have equipment.

 

[2.beans]

im no plumber but if you have a 011 on one side i would think you should have the same on the other side? or have equal flow on each side of the heat exchanger/flat plate. what size pex between the boiler and house? move the water thru the boiler faster and it wont heat up as fast which would keep the boiler running longer. less idle time. i think you still need more draft.

 

[SteveJ]

Kevin,

My Seton was horribly plugged up my first two seasons and I was getting 1200F stack temperatures.

I have a W-130 without storage (soon to be corrected) with 18" horizontal 8" black stove pipe Teed to 24' of 8" DuraVent Class A stainless steel double walled pipe.

My draft is 8-11" w.c.

The beginning of this season I added a TERMOVAR 4440A-3 72C to the supply line from the w-130.

The result has been dramatic - stack temperatures between 400-500F and the hx tubes staying clean.

I did remove the side panel and clean the tubes once and I inserted a piece of angle iron across the intake tubes in front of the exhaust header.

Also, I originally only had one 3/4" pex tube from the supply to my house load and have added several lines in parallel which helped dramatically.

The main operating points I found is for this style boiler are:

1. Minimize idling - preferably by adding pressurized storage and/or more dump zones.

2. Make sure that your supply and return lines can extract at least your rated BTUs - for the W-130 this means 1-1/4" pipe or larger.

3. Provide return temperature protection - keep the return water entering the Seton at least 140F or higher.

As far as cleaning and running, check out the posts from Anthony D, for example https://www.hearth.com/talk/threads/11830/

Steve

Thanks Steve, I am definitely going to be adding a water storage in the near future.. In your operating point #2, I assume when you say supply and return line's being 1-1/4" you are talking about the total area of pex tubing line's going out away from the header on the back of the boiler. Right now, I only have one 3/4" feeding my house and I have another 3/4" going to my shop, but I don't have the shop hx running yet. I am not sure exactly what my return water Temp is, I only have one gauge in the front header of the boiler. When I am running the boiler, the water temp runs at a low of 165degF up to 190degF. Most of the time it run's around 180degF.

Currently I am using my house as the dump zone's. When I build a fire in the evening I go ahead and force my high temp switch on, and that cycles 2 zones on at a time.. Unfortunately by the morning my house is very very hot... And then I let it cool off throughout the day. We don't really like running this way. I think the water storage will smooth out these temp cycles in the future.

Regards,

Kevin

Kevin,

Based on your description and setup, I would suggest two modifications:

1. Install some sort of return water temperature control - like http://na.heating.danfoss.com/PCMPDF/ESBE TV_DS_may09.pdf. My internal heat exchanger tubes were always caked with creosote at the back and down turn until I installed the return water temperature control to keep the return water 150F or above. I have a temp/pressure gauge on both the supply and return lines.

2. Install a more 3/4" pex lines or larger supply and return lines to your house. See Table 1 in (broken link removed to http://www.taco-hvac.com/uploads/FileLibrary/SelectingCirculators.pdf) for "equivalent" number of 3/4" pex to get your rated BTUs from the Seton. Mine is a 130,000 BTU so I would need 13gpm with a 20 degree temperature drop using water. So, I would need to use three 3/4" PEX-AL-PEX supply and three 3/4" PEX-AL-PEX return lines to remove 130,000 BTU from my Seton.

Are you using a flat plate heat exchanger or is the Seton plumbed directly into your house and shop zones?
I ask to see what exchange rate you are achieving.

Steve

Steve, as I mentioned above I only have one 3/4" pex tubing going into the primary side of a plate heat exchanger in the house. I am not sure of the rating on the Hex, it is the same one that came on the back of my boiler when I bought it from Fred, I just moved it into house and replaced it with a header with two supply valves and two return valves. I have not opened the lines going to shop yet. I suspect that my delta between my supply and return is not that great, but I won't know until I get some gauges in.

Are you running two aquastats, one for your damper door and one for your dumpzone? If so, what temp settings do you have them set at.... Based on all information that I am getting, it seems like you have to perfectly balance the heat load to match the boiler so you can keep the water temp just right, and yet keep the damper door open as much as possible.

Regards,

Kevin

Kevin,

I am running three aquastats

1. One to turn the boiler pump on set at 160F with a 5F differential - my boiler protection does not allow flow to the load until about 160F - Termovar AF-4400A3

2. One to control the draft door motor close at 185F with a 20F differential

3. One to dump to my largest zone set at 195F with a 7F differential

You are correct about matching the burns to the loads - trial and error to minimize idling until you have storage.

Steve

 

[PassionForFire&Water]

I have never seen a GW from close by, but by doing some Googeling yesterday evening it's my humble opinion that this wood boiler has no secondary burn above the fire before the flue gasses hit the HX.
No air = No combustion.
Looking at some pictures and noticing that there is no water jacket it seems doable to integrate some secondary air tubes above the fire; just like most of the EPA wood stoves.
This will drastically improve the level of combustion and decrease the creosote formation.
The work involved to put this in is probably equal to the work to clean a clogged-up HX with creosote
I dare to bet that there are probably some Boiler Room guys that did this.

 

[tigermaple]

"Looking at some pictures and noticing that there is no water jacket it seems doable to integrate some secondary air tubes above the fire; just like most of the EPA wood stoves."
It took me two years of operating this beast to come up with that idea and you look at some picts grasp it right away, damn.
When I have to rebuild my GW this is what I would do. Integrating burn tubes between the hex tubes to force air at the creosote, especially in the back. The airflow could be controlled with a simple damper valve. The air would need to be preheated and only flow with the main damper open. I never talked with Fred about this idea, I wonder if he tried it. I don't see a down side if done properly, but ya never know until ya do it.

 

[Pat53]

"Looking at some pictures and noticing that there is no water jacket it seems doable to integrate some secondary air tubes above the fire; just like most of the EPA wood stoves."
It took me two years of operating this beast to come up with that idea and you look at some picts grasp it right away, damn.
When I have to rebuild my GW this is what I would do. Integrating burn tubes between the hex tubes to force air at the creosote, especially in the back. The airflow could be controlled with a simple damper valve. The air would need to be preheated and only flow with the main damper open. I never talked with Fred about this idea, I wonder if he tried it. I don't see a down side if done properly, but ya never know until ya do it.

Tiger, I can assure you that Fred NEVER tried it and would tell you that its not needed. he thinks the Setons burn super-clean now. Just let them idle all day and they stay nice and clean according to Fred ...LOL

I would love to see someone come up with a secondary burn for these units. How hot do you think the secondary air would need to be to work effectively?

Pat

 

[SLEDX509]

Hey guys, I have not looked at other boiler designs too much, But I have started doing some research.. I am assuming that this "Secondary Air" is typical on most "gassifiers"? Would this be comparable to "Overfire Air" on a normal industrial boiler? It's almost embarassing to say, but I work as Control's Engineer at a power utility that burns Biomass in a boiler, and we use overfire air to control our Carbon Monoxide and Excess O2 readings on the backend of our boiler.

Regards,

Kevin

 

[PassionForFire&Water]

Hey guys, I have not looked at other boiler designs too much, But I have started doing some research.. I am assuming that this "Secondary Air" is typical on most "gassifiers"? Would this be comparable to "Overfire Air" on a normal industrial boiler? It's almost embarassing to say, but I work as Control's Engineer at a power utility that burns Biomass in a boiler, and we use overfire air to control our Carbon Monoxide and Excess O2 readings on the backend of our boiler.

Regards,

Kevin

It's certainly comparable, just on a smaller scale.
If you have primary combustion air coming in from below (under-fire) or from the side, then all your oxygen is consumed at the bottom of the fire or somewhere a little higher up.
If there is no over-fire air, typically called secondary air, you have an incomplete combustion with excessive creosote formation when the flue gasses hit the "cold" HX

 

[JrCRXHF]

I only have a few weeks running my Harman SF-260 that i got used. when i got it there was 3/4 to 1" of creosote in the back of the exhaust area and you could not see any daylight between the boiler tubes and the fire box on the top side. I cleaned about 1.5-2 gallons of creosote out of the boiler and did not get it all.

Things i did to cut down on the creosote are:

1. Only try and burn it hard 500F exhaust temp.
2. Wrap the flue from the back of the boiler all the way to the top to keep it as hot as possible
3. Mine does draft control from the bottom but i closed off the idle air and opened the door vents to let it idle when need be.
4. Dry wood and i spray creosote cleaner once or twice a week.
5. I run 1.25" lines to a 75 plate heat ex. return temps are around 5 delta T of supply always over 140. This seems to keep the walls black but not shinny.
6. I turn off the heat once every 3 days or turn it down really low on the gas boiler when i go to work so when i get home i can burn a really hot fire.
7. Keep the wood at the front so it has max time to heat as it runs to the back.

I am still playing around with the boiler getting it dialed in but a fluke IR works great to help you check the temps of the boiler.

I wish i had a gasifier but the price was really cheap on this one and i have no room for storage so this is why i have a old school boiler.

 

[ISeeDeadBTUs]

I have never seen a GW from close by, but by doing some Googeling yesterday evening it's my humble opinion that this wood boiler has no secondary burn above the fire before the flue gasses hit the HX.
No air = No combustion.
Looking at some pictures and noticing that there is no water jacket it seems doable to integrate some secondary air tubes above the fire; just like most of the EPA wood stoves.
This will drastically improve the level of combustion and decrease the creosote formation.
The work involved to put this in is probably equal to the work to clean a clogged-up HX with creosote
I dare to bet that there are probably some Boiler Room guys that did this.

Ahhh! Now see? I'm gonna sound like an ass now -without even trying - but . . . I been dying to ask both SetonClone users AND EuroStyleDownDrafters where and how the secondary air comes in and when? 'Cause I also have been thinking there in NONE on my GW.

Just thinking out loud here, but . . .

If we ran refractory across the top of the primary combustion chamber (similar to the "new and improved" GreenWood) thus forcing the smoke stream to travel the entire length of the tubes, andmade a bypass at the back of the primary combustion chamber, we could isolate the tubes from the smoke. I'm postulating that creosote would not form on the tubes since they wouldn't be subject to idling.

 

[bigburner]

sledx509 - What kind of numbers you guys look for %CO2, %O2 & PPM CO Hey we like controls guys, will fit in here.

 

[SLEDX509]

sledx509 - What kind of numbers you guys look for %CO2, %O2 & PPM CO Hey we like controls guys, will fit in here.

We run anywhere from 2% to 3% excess O2 and anywhere between 150ppm to 200ppm CO. We don't measure CO2 or NOX..... On my boiler at home I have an Allen Bradley PLC reading my thermostats, dump zone high temp switch from my wood boiler and running my Zone Valves, circulator, and electric boiler.. I hope to put some temperature transmitters on my outlet and return lines in the near future, that way I can trend the temps and potentially incorporate them into my PLC program.


Regards,

Kevin

 

[SLEDX509]

Hey guys, I ended up cleaning out my chimney really good last weekend and It has pretty much eliminated my puffing back out the door when I first build a fire. Also I get way less smoke coming back at me when I load the fire. The odd thing to me, is that it's not like the chimney was restricted down to like 2" or 3" diameter opening, it was more like it had a 1/4" to 3/16" hard layer all over the entire surface area of the chimney all the way up. I would not have thought, it would have made that drastic of an impact on the draft.

One more concerning thing, after I had my boiler running for several hours last night with my normal zones running, the boiler was on the verge of overheating. With the normal 2 dump zones running, my water temp was probably around 212degF to 215degF, and It seems as though it would have kept climbing had I not turned on one of my zones in the concrete of the basement. There is no doubt that the two dump zones were taking as much heat as they could because the outlet and return water temps on those zones were much higher than normal. I have built 2 fires since I cleaned the chimney and that is the first time I had experienced that in several years. Is it possible that I am still having too much combustion air coming into the boiler even when the damper is shut? If that is the case, is it going to be worse when I go to an 8" chimney?

Regards,

Kevin

 

[mole]

Good to hear you got the puffing fixed. if your temp is climbing like that while you're idling, then you've prolly got an air leak. It'll be the draft door cover, the firebox door, or the ash pan. I had that problem when I first installed mime. Turned out that I warped the ash pan. Some high temp silicone caulking fixed it. There's some old strings and pictures of peoples' custom gasketing jobs to fix this sort of problem. You just have to do some digging. Anthony D comes to mind.

 

[SLEDX509]

Mole... Thanks for the feedback. I had seen some of those older posts about making gaskets for the damper door, and it seems that most people used a bead of high temp silicone to make a gasket. I was at the Ranch&Home; store the other day and they had some of the that "White Weaved" fabric that they usually put around the inside of wood stove doors, I think it might be made out of NOMOX.... not sure. I was thinking about lining my damper door with that, and possibly my boiler front door. Fred Seton had me fill my ash pit door with SAND before I ever even fired my boiler up, so my ash pit has never been used. I feel the sand gives me a good air break... so to speak.

Oddly enough, my boiler ran all night last night with only two dump zones on and did not seem to overheat. I am not sure what's going on..... I am going to have to a bit more experimenting.

Regards,

Kevin

 

[mole]

Fred Seton had me fill my ash pit door with SAND before I ever even fired my boiler up, so my ash pit has never been used. I feel the sand gives me a good air break... so to speak.

I didn't read the part in the instructions about filling the the ash pit with sand until AFTER my first fire! Not too bright. I don't use my ash drawer either I made an ash scoop out of a short piece of 6"dia stove pipe. Scoops fast and easy.

 

[SLEDX509]

In past years I was constantly cleaning ash out of the bottom, but this year all my firewood was seasoned very very well and for the most part extremely clean i.e.... No dirt from skidding. And I have had little to no ashes left after the fire burns out. I have not had to clean ashes once this year yet... The creosote I am not so lucky with. I have had to clean my chimney and boiler 2 times so far since November.

 

[2.beans]

Good to hear you got the puffing fixed. if your temp is climbing like that while you're idling, then you've prolly got an air leak. It'll be the draft door cover, the firebox door, or the ash pan. I had that problem when I first installed mime. Turned out that I warped the ash pan. Some high temp silicone caulking fixed it. There's some old strings and pictures of peoples' custom gasketing jobs to fix this sort of problem. You just have to do some digging. Anthony D comes to mind.

i sealed all the above mentioned leaks. search me out i probably posted pictures of how i did it. anthony sealed his i believe, he also had pictures if you needed some ideas. ive got mine pretty air tight now. no more creeping temps hitting the dump zone.

 

[SteveJ]

2.beans,

Are you still using the automatic draft damp in the stove pipe to shut off draft when the intake flap closes?

 

[2.beans]

i haven't in a little while. i started to try to make the damper in the stove pipe automatically adjust exhaust temps as the boiler is running so it got unhooked. then new more important projects came up. so its on the to do list. it worked great, it would get the exhaust temps under 175* at idle, but you have to seal the whole boiler up or it can smoke out the feed door or anywhere else it leaks.

 

[Jesse-M]

i haven't in a little while. i started to try to make the damper in the stove pipe automatically adjust exhaust temps as the boiler is running so it got unhooked. then new more important projects came up. so its on the to do list. it worked great, it would get the exhaust temps under 175* at idle, but you have to seal the whole boiler up or it can smoke out the feed door or anywhere else it leaks.

I found this to be true for me as well....

 

[bigburner]

I have been looking at shaft mounted VAV damper motors with pressure ports, I get to much gravity, loss when in no fan mood, but would like it [damper] to float based on draft and/or air in. My vent connector is 24" in diameter so a bunch of heat escaping there.

 

[SLEDX509]

Does having these "automatic dampers" on your exhaust pipes cause more creosote problems for you, if and when they are shut? Trying to get up to speed, it's my understanding that you want to get your entire system designed such that your firing hard and your inlet damper is open most if not all the time? Effectively minimizing the "Idle Time", that causes the smoke/creosote problems.


Regards,

Kevin

 

[bigburner]

Creosote - I am trying to keep heat, when fire low. I have no creosote build up, it all burns in the fire box before the fire tubes, I get fly ash in the tubes. under certain conditions I get some condensation in the chimney vent connector, that's because I rob too much heat from the flue gas.

 

[2.beans]

Does having these "automatic dampers" on your exhaust pipes cause more creosote problems for you, if and when they are shut? Trying to get up to speed, it's my understanding that you want to get your entire system designed such that your firing hard and your inlet damper is open most if not all the time? Effectively minimizing the "Idle Time", that causes the smoke/creosote problems.


Regards,

Kevin

that is correct especially with storage. my goal with the damper in the exhaust was to calm the fire down quickly so the boiler wouldn't creep and hit the dump zone say if the storage was to temp or if you didn't have storage at all. i don't always run mine wide open until the wood is all gone. with my work sometimes its nice when you get home late and the boiler has enough wood in it to get a fire going buy just throwing more wood at it. the storage gives it the long hard run to clean it out regardless of my idle time.